This invention relates generally to auscultatory blood pressure and pulse monitoring method and apparatus. More specifically, it concerns an ambulatory device for the automatic or demand recording and trans-telephonic communication, for later diagnosis, of information including blood pressure, heart rate, time of day, event code and figure of merit. The improved method includes systolic blood pressure-adaptive cuff pressurization and figure of merit computation to ensure that information comfortably, reliably and accurately is monitored and reported.
Typically, ambulatory blood pressure monitoring and recording equipment continuously measures a patient's systolic and diastolic blood pressure for a given period of time. Recent advances in monitoring equipment include the ability of the patient trans-telephonically to communicate information regarding blood pressure to a remote site for permanent storage and either simultaneous or later diagnosis, rather than requiring the patient to return the equipment or a magnetic tape cassette to the physician after each recording session. A serious shortcoming of state-of-the-art equipment is the fact that the pressure cuff which locates the microphone used to pick up auscultatory signals indicative of blood pressure may be less than optimally positioned on the patient's arm, resulting in inadequate signal strength and incomplete or misleading blood pressure data.
Frequently, it is desirable to record blood pressure on demand by the patient, based upon predetermined, physician-selected criteria, e g. upon awakening, while eating or after exercising, rather than continuously or at given times of day that may bear no relation to the individual patient's activity or idiosyncratic behavior. Further, it is desirable continuously to alter the maximum (occlusive) cuff pressure to adapt to the ambulatory patient's level of activity, thereby to ensure that blood flow in the limb is fully occluded but to ensure that the patient's limb is not unnecessarily, and often uncomfortably or even painfully, constricted. Finally, it is desirable to monitor and report to the prescribing physician not only blood pressure and heart rate data, but also information indicative of the quality of, or the figure of merit that may be accorded, such data.
It is a primary object of this invention to provide an ambulatory blood pressure monitoring and recording device capable of indicating to a prescribing physician the quality, or figure of merit, of a contemporaneous or historic blood pressure measurement.
Another object of the invention is to provide such a device that is individual patient physiology- and activity-adaptive, wherein the maximum cuff pressure tracks the rise and fall of the patient's systolic blood pressure, thereby to provide only marginally higher pressure than the amount needed to occlude blood flow in the limb around which the cuff is placed.
These and other objects of the invention will be understood in reference to the following detailed description of the preferred embodiment of the invention, and by reference to the accompanying drawings.